Door mounted alarm assembly

Abstract

An alarm system mounted in a casing intended to be installed in a door. The casing includes a power supply, a noise producing device and a circuit for connecting the power supply to the noise producing device. The circuit includes a key operating device and a mechanism responsive to a detecting knob located on the stile of a door. The key operating device comprises a tumbler switch and a cam operated by the switch which is mounted in the circuit. The mechanism responsive to the knob comprises a hingely mounted plate connected to a spring for biassing the plate in the direction of the cam and the switch. The switch can close the circuit when the door opens and the knob projects outside the stile of the door. Additional cams, tumbler switches and circuits may be combined for producing a variety of alarm producing conditions.

I claim: 
     
       1. An alarm assembly adapted to be mounted inside a door frame, comprising: a casing for housing a power supply, a noise producing device and an electrical circuit, said circuit operating from said power supply for actuating said noise producing device,   a switch mounted in said circuit, said switch having a spring operating lever blade for actuating said switch,   a hinged plate mounted in said casing and a spring for biasing said plate in the direction of said blade and adapted to deflect said blade for actuating said switch,   a knob adapted to be retractedly mounted through one of the lateral faces of a door and to project outside said face, and   a flexible link adapted to be mounted inside said door for connecting said knob to said plate, said knob being normally maintained in a retracted position whereby when said knob is projecting outside said face, said plate is biased in the direction of said blade to deflect the latter and actuate said switch and said noise producing device;   the said assembly further comprising:   a first key operating device having a rotatably spindle,   a first cam mounted on said device and adapted to rotate with said spindle, and   a second switch having a second spring operating blade for actuating said second switch, said first cam mounted adjacent said second blade for actuating the latter upon rotation of said first cam, the said second blade being located adjacent said hinged plate and adapted to inhibit its movement when the knob is in a retracted position, whereby when the door is opened, the knob projects outside said face and the hinged plate is pulled by said flexible link away from said second blade, and said second switch actuates the circuit and the noise producing device.   
     
     
       2. An alarm assembly as recited in claim 1 comprising a second key operating device having a second spindle, a second cam mounted on said device and adapted to rotate with said second spindle, a third switch having a third spring operating blade for actuating said third switch, said second cam mounted adjacent said third blade for actuating the latter, the said third switch being connected to said first and second switches, said second cam being mounted adjacent said third blade of said third switch for closing or opening the circuit passing through the first and second switches. 
     
     
       3. An alarm assembly as recited in claim 2 comprising a luminous indicator mounted on said casing and adapted to be connected to said power supply, the said third switch being mounted between said indicator and said power supply for testing the later. 
     
     
       4. An alarm assembly as recited in claim 2 comprising a pair of wing members pivotally mounted in said casing for blocking apertures provided on said casing, a sliding member adapted to tilt said wing members, said second cam located adjacent said sliding member whereby the rotation of said second cam is adapted to move said sliding member. 
     
     
       5. An alarm assembly as recited in claim 1 comprising a tightly wound metal coil spring mounted over said flexible link for protecting said link. 
     
     
       6. An alarm assembly as recited in claim 1 comprising a spring mounted pin fixed inside said casing and adapted to project outside said casing, a bracket mounted on said spindle located adjacent said pin and adapted to rotate with said spindle, the said bracket being shaped so as to project said pin outside said casing during part of its rotation.